1. Field of the Invention
The present invention is directed to testing of computer software and, more particularly, to providing test data for software executed by a bit-slice microprocessor ordinarily operating on real-time data.
2. Description of the Related Art
Bit-slice microprocessors are small, fast processors with certain limitations. In applications of bit-slice microprocessors, program sequence control is separated from arithmetic processing. Systems using bit-slice microprocessors and microprogram sequencers are commonly used in a wide variety of real-time processing applications in place of hard-wired components to increase flexibility and decrease development time. For example, a single traffic control radar system may use 3 or more bit-slice microprocessors and microprogram sequencers.
One of the functions of air traffic control radar which has been performed by a bit-slice microprocessor is target correlation. The target correlator of the ARSR-3 traffic control radar used by the Federal Aviation Administration of the United States of America includes a bit-slice microprocessor (e.g., an INTEL 3000 or more recently an Advanced MicroDevices (AMD) 29117) operating on 80 bit wide microwords and a microprogram sequencer (an AMD 2910A with a pipeline register). An interrupt controller is used to interface the system with real time data input events. Included on the target correlator board is a 32K by 16 bit data memory (RAM) addressed through a preloadable counter. In normal operation, the data memory is addressed by loading the counter with an address, then presenting data to write to the memory or reading the data output from memory, as required Normal memory access hardware generates memory read and memory write strobes from a single write enable bit in a microcode instruction used to access the RAM.
A bit-slice microprocessor-based target correlator requires system targets and live data to function To make modifications to the target correlator, a method is required to provide simulated target and system data during development and debugging This method should use a minimum of additional hardware, and be capable of providing a high level confidence check of the target correlator during system diagnostic testing. One alternative is to generate the radar data using a simulator or recording of actual data. This requires additional, special purpose hardware which is either very expensive or difficult to use to obtain test data with the desired content. A second alternative is to write a program with "read constant" statements embedded in the program for each piece of data. This can require a lot of space in memory and space is typically limited in bit-slice microprocessor systems. In addition, a significant amount of code is required in the operational portion of the program to access the portion of the program containing test data.